In the general automobile coating process such as the surfacer process and the topcoat process, for the purpose of mass production, a body of an automobile is loaded on a trolley and is conveyed by a conveyer to undergo automatic coating by a robot and a reciprocating coating apparatus.
In the automatic coating in recent years, a rotary atomizer with a bell cup has been often used instead of an air spray gun. Lately, in particular, there has been developed a rotary atomizer having a coating performance improved as compared to a conventional one in such a manner that paint is discharged at a higher discharge rate and is then atomized in a bell cup which is put in very high speed rotation (see Non-patent Literature 1). The use of such a rotary atomizer enables the coating to be performed by a coating apparatus having a smaller number of rotary atomizers than that in a conventional coating apparatus. Moreover, this rotary atomizer can change its spray pattern size, indicating the spread of paint particles to be sprayed, during a coating operation for example. Thus, over-spray, in which some amount of paint is sprayed outside the edge of the object to be coated and wasted, may be prevented, thereby reducing the loss of paint.